Three dimensional computational study for spiral dry gas seal with constant groove depth and different tapered grooves
Leakage is a wide spread phenomenon in the oil and gas production rotating machines. It not only can cause a waste of supplies and energy, but also threats to the safety of people around, due to flammable, explosive, corrosive, toxic working fluid. Advanced sealing technology is the only way to solve the problem. Dry gas seal is a kind of non-contacting dynamic seal used for sealing of rotating shafts. It gets wide applications in petroleum and chemical industries, especially in centrifugal compressors because of high stability and low maintenance. The location of DGS in a typical centrifugal compressor is shown in Fig. 1(a); it is located at the interface between the inside of the compressor and the atmosphere. The seals are fed with a clean, heated if necessary and dry gas usually taken at the discharge of the compressor (1.478Mb)
Gadala, Mohamed S.
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The three dimensional simulation for dry gas seal with constant depth spiral grooves and with different taper grooves is done using ANSYS FLUENT CFD code. Grid independence study and code validation are done with experimental work. The fluid state effect on the gas seal internal flow and performance is studied. The laminar and turbulent flow with RNG K-ɛ turbulence model and LES is examined for the same geometrical and operating conditions. The influence of film thickness for constant depth groove gas seal is simulated for 2, 3 and 4 μm film. The effect of different rotational speeds on gas seal performance is examined for 0, 2500, 5000, 7500 and 10380 rpm. Three taper spiral grooves are studied each with three different angles, including taper grooves in the radial, circumferential and combined radial-circumferential directions. The laminar flow simulation for the dry gas seal agree well with the experimental results more than the turbulent flow simulation which overestimate the pressure distribution inside the seal. The results indicate that as the rotational speed increases the seal open force and leakage increase. The use of tapered type spiral groove causes a reduction in the seal open force and the leakage rate. Increasing the angle of radial taper groove reduces the temperature distribution inside the gas film. The reduction in seal open force and leakage rate is higher when the combined radial-circumferential taper is more than radial and circumferential taper used.